<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>伪类选择器</title>
		<style>
			figure{
				display: flex;
				justify-content: space-between;
			}
			figure div{
				width: 3vw;
				height: 3vw;
				background-color: lightgreen;
				border-radius: 50%;
			}
			/* 选择第7个元素 */
			/* figure div:nth-child(7){
				background-color: #F08080;
			} */
			/* 选择第3个元素及其后所有元素 */
			/* figure div:nth-child(1n + 3){
				background-color: #F08080;
			} */
			/* 选择第奇数个元素 2n+1或者odd */
			/* figure div:nth-child(2n + 1){
				background-color: #F08080;
			} */
			/* 选择第偶数个元素2n或者even */
			/* figure div:nth-child(even){
				background-color: #F08080;
			} */
			/* 选择第5的倍数的元素 */
			figure div:nth-child(5n){
				background-color: #F08080;
			}
		</style>
	</head>
	<body>
		<figure>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
			<div></div>
		</figure>
	</body>
</html>
